Chip mounting has been conventionally performed in a manner such that, as well known, a head holding a chip on an upper level is lowered in a state where a mounting position on a substrate supported on a substrate holding stage on a level below the head is precisely positioned relative to the chip.
Therefore, in advance of such mounting, for example, alignment between the chip and the substrate is performed in a process that recognition marks put on the chip and the substrate are recognized with two-field recognition means and the substrate holding stage is then subjected to movement control in a prescribed manner so as to eliminate a positional discrepancy between both recognition marks, in which the two-field recognition means is moved either in a direction from a retreat position to a recognition position for a recognition mark or in a direction opposed to the former direction for retreat.
Since, as such a process is repeatedly applied to proceed mounting, however, changes in dimension occur in sections of the device due to changes in environmental conditions such as a rise in temperature in a working room, error occurs in positional recognition for a recognition mark if movement control of the two-field recognition means is permanently continued in the same condition, causing difficulty in mounting with a high precision.
Therefore, in order to keep a mounting precision to a μm unit, not only has calibration of a movement control system of the recognition means been performed at any time when required, but various kinds of calibration have also been proposed.
In the description of paragraphs [0036] to [0042] in the specification of JP 97-8104, A, for example, a calibration method is proposed in which a mark table (21) is mounted on a Z table to which a head (corresponding to a bonding tool (17)) is attached with an upward/downward movement mechanism inserted therebetween; the upward/downward movement mechanism is driven not only to move the mark table (21) to a position on the same level as a chip (corresponding to a semiconductor chip (1)) vacuum-suction held by the head, but also to move two-field recognition means (corresponding to integrated cameras (19) and (20)) to a position below the mark table (21) and to thereby recognize a calibration recognition mark (corresponding to a calibration mark (7)) provided on the mark table (21); then, the two-field recognition means is retreated from the recognition position, thereafter the upward/downward movement mechanism is driven not only to move the mark table (21) to a position on the same level as a substrate (corresponding to a circuit substrate (10)) supported on a substrate holding stage (corresponding to a bonding stage (18)) on a lower level, but also to move the two-field recognition means to above the mark table (21) and to recognize the calibration recognition mark; and thereby correcting and updating is performed of a preceding control parameter inputted to the movement control system of the two-field recognition means based on prescribed control parameters obtained by the two recognition operations.
This calibration method, however, has been prevented from performing calibration with a higher precision for reasons that since in the method, the calibration recognition mark provided separately from the recognition marks put on the chip and the substrate, respectively, is recognized at a position spaced widely apart from a recognition position for the recognition marks, a load (a bending moment) acting on a moving table moving the two-field recognition means alters according to whether the two-field recognition means is moved to a recognition position for one (for example, the calibration recognition mark) of the recognition marks or the others thereof (for example, the recognition marks); therefore, a difference between deflections of the moving table caused by different loads results in error in positional recognition of the calibration recognition mark.
The present invention has been made in light of such a fault in the prior art as a result of a serious study conducted in order to rectify the fault based on findings that calibration can be performed with a higher precision by recognizing a first recognition mark put on a head and a second recognition mark put on a stage with first recognition means and second recognition means, respectively, instead of using a conventional mark table and in addition thereto, recognizing the first recognition mark and the second recognition mark in a state of being close to each other with third recognition means.
Note that the present invention makes it possible to mount any of objects in all forms (referred collectively to as a chip) on the side bonded to a substrate, such as an IC chip, an optical element and a wafer, regardless of a kind or a size, onto any of objects in all forms (referred collectively to as a substrate) on the side to which a chip is bonded, such as not only the liquid crystal substrate, but also a resin substrate, a film substrate, an IC chip and a wafer, regardless of a kind or a size, with a high precision.